So, I've tried to increase my Erosion Counter by seeing the Bloody Room event. It is written on this Wiki that this event increases the Erosion Counter by 50, and that after seeing this event there will be blood over the keyboard in Sabitsuki's room. It is also written that when the Erosion Counter reaches 50 or above, there will be blood splatter on the floor of Sabitsuki's room, and that the Little Sabitsuki will become Sick.

After seeing this event, I Got Up, and there was blood over keyboard in the Sabitsuki's room, but there wasn't any blood stains on the floor. I've tried this event five times more, but there still wasn't any blood stains on the floor, and the Little Sabitsuki was Healthy.

What did I do wrong?.flow ver 0.18, English

EDIT: I've tried the Dying Girls event, and that blood stain on the floor appeared. Does that mean that the Bloody Room doesn't affect the Erosion Counter?

Interesting. I never did try to raise the erosion counter myself, mostly because of the fact of what it does to little Sabi.
It's possible that it doesn't stack, and that you'd need to try other events, I can't say for sure though. In any case I can try it myself, but I'm preoccupied with finals and the like this week, so it'll be a bit, assuming no one else replies before then.

I do remember increasing my erosion counter near the ending of the game, I'm not sure if you've beaten it, so I'll digress from detailing it. But some of the more unavoidable events did result in increased erosion, as did the corrupted school event.
Version 0.18 English.

Well, I went to that Deranged Mouth World, where there are many Rust Demons, and increased my Erosion Counter to 200 by interacting with them. And also that Bar Kaibutsu event seemed to increase the Erosion counter.